Process of treating metallic articles.



UNITED STATES PATENT OFFICE.

THOMAS B. ALLEN, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO THE CARBORUNDUMCOMPANY, OF NIAGARA FALLS, NEW YORK, A CORPORATION OF PENNSYLVANIA.

PROCESS OE TREATING METALLIC ARTICLES.

No Drawing.

To all whom it may concern:

Be it known that I, THOMAS B. ALLEN, of Niagara Falls, in the county ofNiagara and State of New York, have invented a Process of TreatingMetallic Articles, of which the following is a full, clear, and exactdescription.

My invention relates to a process of alloy-' methods are accompanied bymany great difficulties, and that articles so formed have very littlemechanical strength, due to the fact that almost all corrosive-resistingsilicides and silicon alloys are very brittle.

I have discovered that if metals are heated in contact with siliconunder suitable conditions, they absorb silicon by a cementation actionat a temperature below the melting points of both the metal and silicon;and that I can thus produce articles having all or part of the surfacecomposed of an alloy of the metal and silicon. The articles thus madeare of great mechanical strength, and are very resistant to the actionof acids and other corrosive substances.

I will now describe a preferred mode of carrying out my invention, andwill use iron as a typical metal, meaning by the term iron all forms andconditions of this material, such as cast iron, malleableiron, steel,etc. It will be understood, however, that I may apply the process to anyor all metals which orni silicides or alloys, especially those which areresistant to the action of corrosive substances.

I take an iron article and first clean itto remove rust, grease, dirtand other similar foreign'materials, by appropriate mechanical orchemical treatment. I then place the article in powdered silicon andheat it to a temperature referably between 700 C. and 1350 C. T esilicon is only applied Specification of Letters Patent.

Application filed August 31, 1910. Serial No. 579,859.

- iron.

Patented Jan. 10, 1911.

to the surfaces where it is desired to obtain the corrosive-resistinglayer, and the other parts of the surface may be covered with some inertmaterial, such as sand. The heating of the article should be carried outin such a manner as to have either a neutral or a reducing atmosphere incontact. with the silicon and the article; since I 'have found that anoxidizing atmos here acts detrimentally, robably by oxi izing the ironarticle and the silicon and thus reventing a proper absorption of thesilicon by the iron. i

The heating is usually continued for a period of from twenty-four toseventy-two hours, during which a ferro-silicon is formed by absorptionof the silicon in the surface portion of thearticle, thisbeing usuallyof crystalline form. I have found that the degree of temperature andlength of heating determine both the depth of the layer of ferro-siliconand also the percentage of silicon in. the alloy, and I may thereforevary the nature of my product by suitably changing the conditions oftreatment. I have also found that when silicon is thus absorbed, it attimes leaves some of the iron unchanged, and on examination, I havefound the interstitlal layers between the crystals of ferrosilicon inthe coating to be composed of The existence of the iron in the intcrstices of the form-silicon is a great disadvantage, and I have foundthat this remaining iron may be converted into ferro-silicon byre-heating the treated article in contact with powdered silicon .in anon-oxidizing atmosphere and at a temperature below the melting point ofthe article and the silicon, thus repeating the original process.

The advantages of m invention will be obvious to those skille in theart. The silicon penetrates the iron in a remarkably uniform manner, andbelow the depth to which the silicon penetrates, the iron is unchanged.As above stated, the silicon which penetrates the iron unites with it toform ferro-silicon; and in articles composed of castiron or high carbonsteels, the silicon also reacts with the iron carbids present to formferro-silicon and precipitate the contained carbon as graphite. Thearticle treated remains practically unchanged as reards its shape and.dimensions when subected to my process. A true absorption or cementationof the silicon by the iron occurs and I can obtain my' finished articlesby forming theminto the desired shape from the iron in any desiredmanner.

I have also found .that ferro-silicon with a high percentage of siliconmay also be used instead of pure silicon, and by the term silicon in myclaims, I intend to cover silicon or its compounds or alloys. Whentreating metals other than iron, the silicon alloys of these metals maypreferably be used in place of ferro-silicon.

I claim:

1. A metallic article having a surface portion composed of an alloy ofsilicon and the metal of the article.

, 2.1. An iron article having at least a part of its integral surfacecomposed of ferrosilicon.

' 3. As a new article of manufacture, a

metallic article having a surface portion impregnated or alloyed \vithcemented silicon.

4. The process of treating metal articles which consists in heating saidarticles with silicon to a temperature below the melting points of themetal and the silicon.

The process of. forming a corrosive resisting surface on metal articleswhich consists in heating said articles in contact with silicon to atemperature below the melting point of the metal and silicon, in anonoxidizing atmosphere.

6. The process of converting a surface portion of a metal article intoan alloy of silicon, which consists in heating said article in contactwith silicon to a temperature below the melting point of silicon in anonoxidizing atmosphere.

7. The process of formin a corrosive-resisting surface on metalartlcles, which consists in heating said articles with silicon to atemperature below the melting point of the metal and silicon, andre-heating said article with silicon to a temperature below the meltingpoint of the metal and silicon.

8. The process of forming a corrosive-resisting surface on metalarticles, which consists in heating said articles with silicon to atemperature below the melting point of the metal and silicon in anon-oxidizing atmosphere, and re-heating said article with silicon to atemperature below the melting point of the metal and silicon in anonoxirlizing atmosphere.

In testimony whereof, I have hereunto set my hand.

THOS. B. ALLEN. \Vitnesses EDMUND S. SMITH, R. B. MANLEY.

